Make QStateMachine inherit QState

This removes the need for a "root state" in the machine; or rather,
the machine _is_ the root state.
User code can now pass in a QStateMachine directly to the QState
constructor, instead of machine->rootState().
This also means we could get rid of the "proxying" from the machine
to the root state for things like properties (initialState et al),
finished() signal and auto-reparenting of states (the ChildAdded
event hack).
A fun little side-effect of this change is that it's now possible
to embed state machines within state machines. We can't think of
a good use case yet where you would rather embed a stand-alone
state machine (with its own event processing etc.) rather than
having just a regular nested state, but it's neat and it works.

Reviewed-by: Eskil Abrahamsen Blomfeldt

1 files changed, 5 insertions, 17 deletions

diff --git a/src/corelib/statemachine/qstatemachine.h b/src/corelib/statemachine/qstatemachine.h
index 30d0e3a59d..230d8525ba 100644
--- a/src/corelib/statemachine/qstatemachine.h
+++ b/src/corelib/statemachine/qstatemachine.h
@@ -42,7 +42,7 @@
 #ifndef QSTATEMACHINE_H
 #define QSTATEMACHINE_H
 
-#include <QtCore/qabstractstate.h>
+#include <QtCore/qstate.h>
 
 #include <QtCore/qlist.h>
 #include <QtCore/qobject.h>
@@ -57,18 +57,12 @@ QT_MODULE(Core)
 #ifndef QT_NO_STATEMACHINE
 
 class QEvent;
-class QAbstractState;
-class QState;
 
 class QStateMachinePrivate;
 class QAbstractAnimation;
-class QAbstractState;
-class Q_CORE_EXPORT QStateMachine : public QObject
+class Q_CORE_EXPORT QStateMachine : public QState
 {
     Q_OBJECT
-    Q_PROPERTY(QState* rootState READ rootState)
-    Q_PROPERTY(QAbstractState* initialState READ initialState WRITE setInitialState)
-    Q_PROPERTY(QAbstractState* errorState READ errorState WRITE setErrorState)
     Q_PROPERTY(QString errorString READ errorString)
     Q_PROPERTY(RestorePolicy globalRestorePolicy READ globalRestorePolicy WRITE setGlobalRestorePolicy)
     Q_ENUMS(RestorePolicy)
@@ -94,14 +88,6 @@ public:
     void addState(QAbstractState *state);
     void removeState(QAbstractState *state);
 
-    QState *rootState() const;
-
-    QAbstractState *initialState() const;
-    void setInitialState(QAbstractState *state);
-
-    QAbstractState *errorState() const;
-    void setErrorState(QAbstractState *state);
-
     Error error() const;
     QString errorString() const;
     void clearError();
@@ -135,9 +121,11 @@ public Q_SLOTS:
 Q_SIGNALS:
     void started();
     void stopped();
-    void finished();
 
 protected:
+    void onEntry(QEvent *event);
+    void onExit(QEvent *event);
+
     void postInternalEvent(QEvent *event);
 
     virtual void beginSelectTransitions(QEvent *event);